Would he think I was just saving him because he's a "lost puppy"?

Well first of all i wouldn't like a guy who was smoking pot but if you do go for it. If you talk to him first u have to make sure that he's not high.Tell him that u really miss the way things were and ask him if u could ask him to be nicer to you. There is like a 50% Chance that he would think it was charity, but there is also a 50% chance that he won't. If he does think it's charity you just need to keep working at it until u guys are friends again!